Design and Implementation of Graphene-Based Tunable Microwave Filter for THz Applications

Area of Science:

• Terahertz (THz) technology
• Microwave engineering
• Materials science

Background:

• Substrate-Integrated Waveguide (SIW) filters are crucial components in modern communication systems.
• Achieving reconfigurability in THz filters is essential for advanced signal processing and tunable applications.
• Graphene's unique electronic properties offer potential for tunable microwave and THz devices.

Purpose of the Study:

• To design and demonstrate a reconfigurable Substrate-Integrated Waveguide (SIW) filter operating in the terahertz (THz) frequency range.
• To investigate the tunability of the SIW filter using graphene via electrical bias and geometrical modifications.
• To analyze the impact of these tuning mechanisms on the filter's center frequency and bandwidth.

Main Methods:

• A second-order SIW filter was designed using a double-layer substrate (silicon and silicon dioxide) coupled via a magnetic iris.
• Graphene was integrated as a tunable element sandwiched between the dielectric layer and the upper ground plane.
• The filter's center frequency was tuned by applying an external DC bias voltage to modulate graphene's chemical potential and by altering the graphene patch's aspect ratio.

Main Results:

• Electrical tuning using DC bias shifted the filter's center frequency from 1.289 THz to 1.297 THz, achieving an 8 GHz bandwidth tuning range.
• Geometrical tuning by changing the graphene patch aspect ratio resulted in a frequency shift within the range of 1.2908 THz to 1.2929 THz, with a 2.1 GHz bandwidth change.
• The proposed design demonstrates effective tunability for THz SIW filters.

Conclusions:

• The developed graphene-tunable SIW filter offers a viable solution for reconfigurable THz systems.
• Both electrical and geometrical tuning methods provide effective control over the filter's operational frequency.
• This work contributes to the advancement of tunable components in the THz frequency spectrum.